I. Field of the Invention
This invention relates generally to myocardial revascularization cardiac surgery, and more particularly to an improved method and apparatus for performing coronary lesion bypass to restore patency to blocked coronary or stenotic arteries.
II. Discussion of the Prior Art
Coronary artery disease is a major cause of death in the United States. The disease results in the build-up of calcified, fibrous and fatty deposits on the walls of the coronary arteries supplying blood to the myocardium. The narrowing of one or more cardiac arteries often results in ischemia, leading to angina pain. Moreover, clots may result in blockage of the flow of blood through a blood vessel that has been narrowed by the stenotic lesion, resulting in myocardial infarction or unstable angina.
One approach for restoring patency to a narrowed coronary artery is commonly referred to as "balloon angioplasty". Here, a catheter having an inflatable expanding member on its distal end is routed through the vascular system until the yet uninflated member is juxtaposed with the lesion to be treated. Saline and/or contrast is then introduced through a lumen in the catheter to the interior of the expander member with sufficient pressure to inflate the expander member and fracture or compress the lesion into the wall of the blood vessel. When the expander member is deflated and the catheter removed from the patient, patency is restored to the affected coronary artery.
Not all patients suffering from coronary artery disease are candidates for balloon angioplasty. A significantly more invasive procedure, commonly referred to as coronary bypass surgery, may then be called for. In this procedure, the sternum is divided and retractors are used to expose the chest cavity. The pericardial sack is opened and the patient is placed on a heart/lung machine, allowing the patient's own heart to be stopped. A vascular segment, which may be harvested from the patient's saphenous vein or the internal mammary or radial artery, is then anastomosed to the blocked artery beyond the point of obstruction to thereby provide a shunt blood path along that lesion. Once the necessary bypass segment(s) have been sutured in place, the heart is then restarted, the chest wall is reanastomosed together and the surgical incision closed.
Such coronary bypass surgery is not only quite expensive in terms of medical costs, but also in terms of the relatively lengthy time required for recuperation.
A need exists for a less traumatic coronary bypass procedure. Some medical centers have recently reported on minimally invasive surgery wherein the bypass procedure is conducted through a relatively small wound in the chest and rib cage, with drugs being given to slow the heart rate. At this point, however, such a procedure is not widely practiced and can only be performed in selective cases where reasonable access can be had to the coronary artery containing the stenotic lesion.
A real need exists for a catheter based procedure for performing coronary bypass in those cases where balloon angioplasty is determined to be ineffective. It is the principal purpose or object of the present invention to provide such a new technique as well as instruments and devices for carrying out the procedure.